1. Technical Field
The present invention generally relates to a contact portion of wiring and a method of manufacturing the contact portion of wiring and, more particularly, to a thin film transistor array panel including the contact portion of wiring and a method of manufacturing the thin film transistor array panel including the contact portion of wiring.
2. Related Art
Generally, it is preferable that an area of a semiconductor element is optimized and that wiring thereof is formed with a multi-layered structure as the semiconductor element is highly integrated. To minimize the interference of a signal transmitted through the wiring, an insulating layer is preferably made of a material having a low dielectric constant, and wires that transmit the same signal are connected to each other through a contact hole of the insulating layer. When etching the insulating layer to form the contact hole, if an undercut is generated at the contact portion, step coverage of the contact portion may be degraded. The profile of the wiring formed on the insulating layer may, thus, deteriorate, and disconnection of the wiring may occur at the contact portion.
Such wiring may be useful, for example, for a liquid crystal display (LCD). The liquid crystal display is one of the most commonly used types of flat panel displays. An LCD typically includes two substrates with electrodes formed thereon and a liquid crystal layer interposed between the two substrates. In the LCD, a voltage is applied to the electrodes to realign liquid crystal molecules of the liquid crystal layer to thereby regulate the transmittance of light passing through the liquid crystal layer.
Among liquid crystal displays, a liquid crystal display having a structure in which field generating electrodes are respectively formed on two display panels and having a thin film transistor for switching voltages applied to the field generating electrodes is widely used. Generally, the panel having the thin film transistor includes wiring including a gate line transmitting a scanning signal and a data line transmitting an image signal, and a gate pad and a data pad receiving the scanning signal or the image signal from an external circuit and transmitting the signals to the gate line and the data line. A pixel electrode electrically connected to the thin film transistor is formed in a pixel area defined by an intersection of the gate line and the data line.
In order to improve the display characteristics of the liquid crystal display, it is important to obtain a sufficient aperture ratio of the pixel. For this object, the wiring and the pixel electrode overlap each other, and an insulating layer made of an organic material having a low dielectric ratio to minimize the signal transmitted through the wiring is formed therebetween.
In manufacturing the thin film transistor array panel for the liquid crystal display, it usually is necessary to expose the wiring for connection to the pad for receiving the signal from the external circuit or for connecting the wires to each other. When forming the contact hole at the lower layer, however, by etching the lower layer using the insulating layer having the contact hole as an etch mask, if the contact hole exposing the pad or the wiring is formed in the condition that the insulating layer is not etched to secure (e.g., preserve) the thickness of the insulating layer, the lower layer typically is severely undercut under the insulating layer such that the step coverage of the contact portion deteriorates. Accordingly, the profile of the other, upper layer may be degraded, or the upper layer may be disconnected at the contact portion.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.